Investigation of Reduction Mechanism and the Effect of NaCl-CaCl2 Mixture on Tungsten Production from Tungsten Sulfide

Abstract

Tungsten powder production from its sulfide by constant voltage electrochemical reduction was studied in CaCl2-NaCl salt solutions by varying composition at 750 °C. The mechanism of the reduction process was investigated by means of linear sweep voltammetry analysis using three electrodes; tungsten reference, graphite and WS2 porous pellet in eutectic CaCl2-NaCl salt mixture. The characterization studies were performed by X-ray Diffraction analysis and Scanning Electron Microscope. The produced powder contained tungsten produced by the complete reduction of WS2 with some by-products containing mainly Ca compounds. Tungsten could be separated successfully from the by-products after an acid treatment using dilute HCl. Furthermore, it was observed that the increase in CaCl2 could lead to an approximate doubling of the reduction rate within the parameter ranges covered in this study.